The Test Tiles Lied!

So I did make test tiles, They look beautiful. My pots look awful. I mostly have pitting and some running off the pots over the drip line. I glazed the tiles and pots at the same time and they were in the same kiln load. The tiles are for making a glaze sample board like someone else posted. The only difference was the tiles were dipped and the pots were glazed by pouring. The pots were really dry. They had been bisqued to cone 04. I am using Highwater Little loafers, and Laguna Moroccan Sand dry glazes. I fire to cone 6. Did glazing by pouring really make that big of a difference? How do I fix this problem? I don't have large enough quantities of glaze to dip everything. I appreciate your replys.

So I did make test tiles, They look beautiful. My pots look awful. I mostly have pitting and some running off the pots over the drip line. I glazed the tiles and pots at the same time and they were in the same kiln load. The tiles are for making a glaze sample board like someone else posted. The only difference was the tiles were dipped and the pots were glazed by pouring. The pots were really dry. They had been bisqued to cone 04. I am using Highwater Little loafers, and Laguna Moroccan Sand dry glazes. I fire to cone 6. Did glazing by pouring really make that big of a difference? How do I fix this problem? I don't have large enough quantities of glaze to dip everything. I appreciate your replys.

-chantay

Assuming the tests and pots got the same heat work (not in different temp zones in the kiln) I think the difference is due to the application. Compared to dipping, pouring is less exact. It is easy to get too much or too little glaze on the pot by overlapping (too thick) and not enough time on pot for enough to stick (too thin). If you can't dip, spraying may be an improvement over pouring. If you can't spray or dip try pouring much more carefully.

It's difficult to say what happened without seeing the difference. I also say that it is in the application. Dipping allows glaze to absorb longer and the glaze goes on more evenly. I know with these commercial glazes that you won't have enough to dip everything. The other issue is that the tiles will lie flat, and your pots would be vertical, somore tendency for uneven surface. Ain't pottery fun?
TJR.:Dsrc="http://ceramicartsda...t/biggrin.gif">

It's difficult to say what happened without seeing the difference. I also say that it is in the application. Dipping allows glaze to absorb longer and the glaze goes on more evenly. I know with these commercial glazes that you won't have enough to dip everything. The other issue is that the tiles will lie flat, and your pots would be vertical, somore tendency for uneven surface. Ain't pottery fun?TJR.:Dsrc="http://ceramicartsda...t/biggrin.gif">

Good point about the tiles being fired flat. I just assumed a test tile would be the kind that stand up. A flat test tile is a bad idea because the difference between a glaze on a horizontal and a vertical surface could be very significant.

I learned to make test tiles from a small (6 inch round) thrown pie plate form cut into small sections.
That way you get to see the glaze on a horizontal surface and a vertical surface which shows you a truer test.
Glaze application is a learned skill-this all takes time-My only other suggestion is to just do a lot more glazing/learning.
Mark

The test tiles were the type that stand up. I also had some flat tiles, they look good also. I put the glaze on very evenly. I have been working on that, so there isn't any overlapping areas. I guess I will try a second poured coat. I thought about spraying, but I'm not really making that much stuff and not ready to buy a spray set up. It seems to me that when you spray, a spray booth is really needed. Is there any way around a booth with an exhaust? More testing.....

-chantay

Edit:

the test tiles where scattered through out the kiln and it is firing evenly.

Next time single dip and double dip a part of each tile-this gives you two tests in one-then next step is lip dip other glazes overs the lip for more combinations-
I learned this in glaze calc &nbsp;class from some recent Alfred Grads back in the early 70's who got jobs at the college I attended.
My career as a functional potter was jump started from these guys.
You will learn so much from a good set of test tiles.
Now fast forward 40 years and most of my work has 4-5 glazes on each piece-I still do a little two tone work but it sells far slower.
Mark

The test tiles were the type that stand up. I also had some flat tiles, they look good also. I put the glaze on very evenly. I have been working on that, so there isn't any overlapping areas. I guess I will try a second poured coat. I thought about spraying, but I'm not really making that much stuff and not ready to buy a spray set up. It seems to me that when you spray, a spray booth is really needed. Is there any way around a booth with an exhaust? More testing.....

-chantay

Edit:

the test tiles where scattered through out the kiln and it is firing evenly.

You may decide to get a spray booth if you want to get more involved with spraying but you certainly don't need one to get started. The only reason to get a spray booth is the obvious problem of working on days when it is bitterly cold. Almost all my glazing is spraying and I had a booth but got rid of it because I'd rather deal with the cold (Okay, I admit I'm in Georgia so that's not as big a problem as for someone in Alberta but I have glazed when the temp was in the 20's.) than the many disadvantages of having a spray booth in my studio. If you have a compressor all you need is a general purpose gun for auto painting and one for detail (or you could use airbrush for detail). If you don't have a compressor Harbor Freight has all you need to get started for under $100. http://www.harborfre...-kit-44677.html

But, with all that said, rather than buying a spray gun, I'd start mixing my own glazes so that I could make enough to dip pots.

Spraying allows for a great finish . . . just remember there is a learning curve to glaze spraying to get the right thickness of application, just as there is a learning curve to dipping, pouring, etc. Spraying may help if you are using pints of commercical glazes that don't allow for dipping. But there will be trial and error to get the right consistency in the sprayer and the right thickness on the pots. And, you need to learn how to handle a sprayed pot so you don't leave fingerprints or smudges. Still, it's worth the effort. But expect to put in some practice time . . . maybe using india ink or thinned tempra paints to learn how to apply with a sprayer.

Before I got a spray booth, I sprayed my pots in an unheated garage by setting a large (think water heater or refrigerator) box on top of an old ping-pong table. The box also works outside to more or less contain the overspray and concentrate it on your pot that's sitting on a banding wheel (or something similar). I prefer spraying because I'm a total klutz with glazes and spraying is the only way I can get even coverage. I didn't have funds to begin with and found an electric paint sprayer (no compressor needed) worked just fine as long as you shake the sprayer every two minutes.

I have also been making simple little cups and bowls to use as testers. I try different texture glaze combos on them too. Then it is fun to have a bunch of little vessels when you need to grab something to hold stuff, or whatever.

I think I will look into a spray gun. I already have an air compressor. Where I live the temps are pretty mild and I could probably work outside 10 out of 12 months. I usually use small pots for glaze testing, but I wanted to make the tiles to hang on the wall. Some of the tiles that do look good, the hole for hanging filled with glaze even though I didn't put any in it. I'm guessing that wax will fix that.

So I did make test tiles, They look beautiful. My pots look awful. I mostly have pitting and some running off the pots over the drip line. I glazed the tiles and pots at the same time and they were in the same kiln load. The tiles are for making a glaze sample board like someone else posted. The only difference was the tiles were dipped and the pots were glazed by pouring. The pots were really dry. They had been bisqued to cone 04. I am using Highwater Little loafers, and Laguna Moroccan Sand dry glazes. I fire to cone 6. Did glazing by pouring really make that big of a difference? How do I fix this problem? I don't have large enough quantities of glaze to dip everything. I appreciate your replys.

-chantay

A few questions to ask that I did not see asked. Did you wash the pots with a damp sponge before glazing? This helps to remove dust that causes pin holing, and puts a small amount of water in the ware to cut glaze absorption giving you a more even thickness of glaze. How thin did you mix the glaze to pour? If you had placed your hand in the glaze would you have gotten an even coat where you could see you cuticles at the fingernails or would it have covered more like a rubber glove? Answers to these questions may help pin down the problem.

I think I will look into a spray gun. I already have an air compressor. Where I live the temps are pretty mild and I could probably work outside 10 out of 12 months. I usually use small pots for glaze testing, but I wanted to make the tiles to hang on the wall. Some of the tiles that do look good, the hole for hanging filled with glaze even though I didn't put any in it. I'm guessing that wax will fix that.

-chantay

Wax won't prevent the glaze from running into the hole as it will melt away way before the glaze runs. Scratch away the glaze from around the hole a bit.

I think I will look into a spray gun. I already have an air compressor. Where I live the temps are pretty mild and I could probably work outside 10 out of 12 months. I usually use small pots for glaze testing, but I wanted to make the tiles to hang on the wall. Some of the tiles that do look good, the hole for hanging filled with glaze even though I didn't put any in it. I'm guessing that wax will fix that.

-chantay

You don't have to get an expensive spray gun to try spraying. You can try a mouth blower like the Van Gilder siphon. I got one from Baily Ceramics (http://www.baileypot...Gildertools.htm) for under $30. I'm thinking of attaching the exhaust hose of my vacuum cleaner to it.